Module Comprising a Semiconductor Chip

ABSTRACT

A module includes a semiconductor chip having at least a first terminal contact surface and a second terminal contact surface. A first bond element made of a material on the basis of Cu is attached to the first terminal contact surface, and a second bond element is attached to the second terminal contact surface. The second bond element is made of a material different from the material of the first bond element or is made of a type of bond element different from the type of the first bond element.

This is a divisional application of U.S. application Ser. No.11/725,973, entitled “Module Comprising a Semiconductor Chip,” which wasfiled on Mar. 20, 2007 and is incorporated herein by reference

TECHNICAL FIELD

The invention relates to a module comprising a semiconductor chip and invarious embodiments to an electrically bonding of the semiconductorchip.

BACKGROUND

Various techniques are available to electrically connect a semiconductorchip in a module to external terminals of the module. For example,clip-bonding, ribbon-bonding or wire-bonding are techniques known in theart. Further, various different materials have been used for the bondelement, among them Al, Cu or Au. The selection of the bonding techniquemay have a significant impact on the overall manufacturing costs andperformance of the module.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the invention are made more evident by way of example in thefollowing detailed description of embodiments when read in conjunctionwith the attached drawing figures, wherein:

FIG. 1 is top view of an embodiment of a module;

FIG. 2 is a cross sectional view along line A-A shown in FIG. 1;

FIG. 3 is a top view of another embodiment of a module;

FIG. 4 is a cross sectional view along line B-B shown in FIG. 3;

FIG. 5 is a top view of a further embodiment of a module;

FIG. 6 is a cross sectional view along line C-C shown in FIG. 5;

FIG. 7 is a top view of the module shown in FIG. 3 comprising a moldcompound;

FIG. 8 is a side view of the module shown in FIG. 7;

FIG. 9 is a footprint of the module shown in FIG. 7;

FIG. 10 is top view of a further embodiment;

FIGS. 11 a-11 c, collectively FIG. 11, show illustrations of a capillarytool used for wedge wire-bonding;

FIGS. 12 a-12 c, collectively FIG. 12, shows illustrations of acapillary tool used for ball wire-bonding;

FIG. 13 is a flow chart illustrating processing steps for manufacturinga module;

FIG. 14 is a schematic diagram illustrating an embodiment of aprocessing line for manufacturing modules; and

FIG. 15 is a schematic diagram illustrating another embodiment of aprocessing line for manufacturing modules.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Modules described in the following comprise at least one electroniccomponent such as a semiconductor chip. The electronic component can bea power semiconductor chip or a chip operating in the standard power(i.e., non-power) regime, e.g., a logic integrated circuit or a sensorchip, e.g., a CCD (charge coupled device) or for instance a MEMS(micro-electronical mechanical structure) such as a pressure sensor etc.

A power semiconductor chip may have a power consumption that spans overa wide range, starting from about one or several amperes and about fiveor more volts to several hundreds of amperes or several hundreds ofvolts. For example, a power semiconductor chip may be a MOSFET (MetalOxide Semiconductor Field Effect Transistor), JFET (Junction FieldEffect Transistor), IGBT (Insulated-Gate Bipolar Transistor), BJT(Bipolar Junction Transistor) or thyristor.

The semiconductor chip may be a vertical semiconductor device or ahorizontal semiconductor device. A vertical semiconductor device has atop face with a first contact surface and a bottom face with a secondcontact surface. The load current flows in a vertical direction betweenthe top contact surface and the bottom contact surface. In contrastthereto, in a lateral semiconductor device, both load current contactsurfaces are arranged on the top face of the semiconductor chip.

The module may be packaged, i.e., may comprise a mold compound. The moldcompound may, for example, be made of a thermoplastic resin or athermosetting plastic, for example epoxy resin. It typically encapsulateone or more chips of the module. A backside of a carrier on which thechip or the chips are mounted may either be over-molded by the moldcompound or may remain exposed. It is also possible that the chipcarrier(s) or the chip(s) are connected to a heat sink which remains atleast partially uncovered by the mold material.

FIG. 1 shows a module comprising a semiconductor chip 1 having a topsurface 2 and leads 3, 4 which may represent external terminals forelectrically connecting the semiconductor chip 1 to an externalassembly, for instance a circuit board or another mounting platform onwhich the module is to be mounted. The top surface 2 of thesemiconductor chip 1 comprises two conductive contact areas 5, 6. Thecontact areas 5, 6 are insulated from each other.

The contact area 6 of the semiconductor chip 1 is interconnected to apost area 4 a of lead 4 by a bond wire 7 which is typically made on thebasis of Cu, e.g., may be made of Cu or of a Cu metal alloy. Such Cuwires may contain more than 90 wt % Cu and contributions of other metalelements such as Ni, Fe etc. Further elements such as P, S may be addedin low concentrations (usually smaller than 1 wt %) to control thephysical characteristics of the wire. The contact area 5 of thesemiconductor chip 1 is interconnected to a post area 3 a of the lead 3by an electrically conductive bond element 8.

In non-power semiconductor chips, the contact areas 5, 6 may be commonchip contact pads used for any signals such as digital input/outputsignals or power supply. In power semiconductor chips, the contact area5 may be a load current contact area, e.g., the drain or sourceelectrode of a power transistor implemented in the semiconductor chip 1.The contact area 6 may be a control signal contact area, e.g., the gateelectrode of such power transistor.

According to a first embodiment, the bond element 8 may be made of amaterial different from the material of which the bond wire 7 is made,e.g., different from Cu or a Cu metal alloy. The bond element 8 may forinstance be an Al or Au bond wire. Al bond wires are typically used forcontacting load electrodes of a power semiconductor chip to externalterminal leads since Al (other than Cu) provides the possibility to uselarge diameter wires capable of transporting high currents. However, forproviding a large cross section for high current transport, bond element8 may also be a clip- or ribbon-bond element made of a materialdifferent from the material of bond wire 7. Such clip- or ribbon-bondelement may also be made of Al.

As will be explained in more detail later, the concept of usingdifferent bond element materials may provide for a reduction of thetotal costs involved in bonding the semiconductor chip 1 to leads 3, 4.That is because bond wires made on the basis of Cu may be bonded by aninexpensive ball wire bonding process and Cu is a low cost material.Further, ball bonding a Cu bond wire is more than an order of magnitudefaster than, e.g., wedge wire bonding an Al bond wire. These effects maymore than compensate any potential extra expenditure caused by the usageof two different bond element materials.

According to another embodiment, the bond wire 7 and the bond element 8may distinguish from each other in that they are necessarily ofdifferent type. The bond element 8 has a rectangular shaped crosssection, i.e., is no wire. Again, bond wire 7 is made on the basis ofCu, e.g., may be made of Cu or of a Cu metal alloy. The bond element 8may be a clip- or ribbon-bond element. It may be made of a materialbased on Cu. Further, as already stated in relation with theaforementioned aspect of using different bond element materials, thebond element 8 may be made of materials different from Cu, e.g., Al orAu.

Typically, the lateral dimension W of the bond element 8 is larger thanthe diameter of bond wire 7. Therefore, higher currents may flow throughbond element 8 than through bond wire 7. The lateral dimension W of bondelement 8 may be larger than 0.5 mm for a ribbon-bond element 8 (cf.FIG. 2) and may also be larger than 0.5 mm (but may even have a lateraldimension W of the same order as the lateral dimension of thesemiconductor chip 1) for a clip-bond element (cf. FIG. 6).

The aspects of using a bond wire made on the basis of Cu for bonding onecontact area 6 of the semiconductor chip 1 and using a bond element ofdifferent material and/or different type for bonding another contactarea 5 of the semiconductor chip 1 may provide technological benefitbecause they allow to use a material and/or type of the bond element 8which is optimum for the physical requirements (for instance highcurrent) of the respective electrical connections.

In FIG. 3 the semiconductor chip 1 is mounted on a die pad 10. The samereference signs used throughout the figures reference similar partstherein. The die pad 10 forms part of a leadframe 11. The leadframe 11is a structured sheet of metal, for instance Cu. This structured sheetof metal further comprises a lead 3 terminated by a post area 3 a, alead 4 terminated by a post area 4 a and a lead 12 forming an integralextension of the die pad 10.

The semiconductor chip 1 may be a vertical p-type power transistor. Inthis case, the die pad 10 is connected to the drain (D) contact area ofthe transistor, as the drain (D) contact area is located at the bottomface of the semiconductor chip 1. The top face of the semiconductor chip1 carries a source (S) contact area 5 and a gate (G) contact area 6. Thesource contact area 5 is interconnected to the post area 3 a of lead 3by a bond element 8 (for instance a thick Al or Au bond wire or aribbon-bond element made, e.g., of Cu or Al) and the gate contact area 6is interconnected to the post area 4 a of lead 4 by a bond wire 7 on thebasis of Cu.

Leads 3, 4, 12 may serve as external terminals of the module. Lines 13indicate a bend zone at which leads 3, 4, 12 are expected to stick outof a package which may be applied later. Further, frame bars 14interconnecting the leads 3, 4, 12 will be cut-off at a later stage ofthe manufacturing process such that leads 3, 4, 12 will be insulatedfrom each other in the finished module.

The bond wire 7 may have a diameter in the range between 10 and 200 μm.As typically only small currents are transferred via bond wire 7, thediameter of bond wire 7 may in many cases be smaller than 50 μm. Thesmaller the diameter the smaller the unavoidable damage to therespective contact area and the structure below the contact area. Thisholds especially true for a Cu bond wire which is usually harder than,say, an Al bond wire.

If the semiconductor chip 1 is a power device, the cross-sectionaldimensions of bond element 8 should be large enough in order to allowfor the transfer of load currents that may have a considerable magnitude(for instance up to several hundreds of amperes). Thus, if the bondelement 8 is a bond wire, the bond wire 8 (made, e.g., of Al) may have adiameter in the range between 50 and 800 μm.

It is to be noted that a bond wire 7 on the basis of Cu is a factor ofthree less expensive than a bond wire made of Al. Further, as will beexplained in more detail in the following, the process of bonding a Cubond wire involves considerable less costs than the process of bondingan Al bond wire because the process of bonding a Cu bond wire is aboutten times faster than the process of bonding an Al bond wire (e.g., 0.1s in comparison to 1 s). Therefore, the concept of “mixed bonding”proposed herein provides substantial benefits compared to a process inwhich solely Al bond wires are used.

Otherwise, if the bond element 8 has a rectangular cross section, cf.FIG. 4, the bond element 8 may be a ribbon-bond made of Cu or Al. Thelateral dimension W may be chosen as indicated above for ribbon-bonds.

FIG. 5 shows a module that differs from the module shown in FIGS. 3 and4 mainly in that the bond element 8 is a clip-bond element. As shown inFIG. 6, similar to a ribbon-bond element 8, a clip-bond element 8 has arectangular cross section. However, contrary to the ribbon-bond element8, the clip-bond element 8 has a flat lower surface 8 a that makescontact with the contact area of the chip 1 across a large area. Forexample, if the chip 1 is a vertical p-type power transistor like inFIG. 3, the size of the lower surface 8 a of the clip-bond element 8 ischosen to cover all, or almost all of source contact region 5. This way,compared to a ribbon-bond element 8, a significantly larger current canbe carried from the clip-bond element 8 to the chip 1. Further,different from a ribbon-bond element 8, clip-bond elements 8 aresoldered to the respective contact area of the chip 1. Typically, asalready mentioned, the width W of a clip-bond element 8 is larger thanthe width W of a ribbon-bond element 8. Thus, as an example, multipleleads 3 may be bonded to the clip-bond element 8 in order to meet highcurrent demands.

Similar to a ribbon-bond element 8, the clip-bond element 8 can be madeof a material on the basis of Cu or Al, and the bond wire 7 may be madeof a material on the basis of Cu.

It is to be noted that corrosion on a Cu pad is minimum if a bond wire 7made of Cu is bonded to a Cu pad. Thus, in all embodiments where thecontact area 6 on semiconductor chip 1 is made of Cu, a high corrosionresistance of the semiconductor chip bond is achieved.

It is further to be noted that, if the leadframe 11 is made of materialon the basis of Cu, it is not necessary to apply any coating to the postareas 3 a and 4 a because both a Cu bond wire as well as an Al bond wiremay be contacted directly to a Cu surface. At the Cu—Cu contact,corrosion is again minimized. This further reduces costs in comparisonwith alternate bonding approaches. For instance, the usage of Au bondwires 7, 8 would require to apply an Ag or Au coating on the post areas4 a and 3 a, respectively.

On the other hand, bond wires on the basis of Cu may be harder than bondwires made of alternate materials like Al or Au. Therefore, especiallyif thick Cu bond wires are used, there could be a risk that the bondmight damage or even break the conductive contact area on thesemiconductor chip and thus could cause failure of the semiconductorchip 1. As the bond element 8 is a wire made of a material differentfrom Cu or a bond element of different type than a wire (e.g., a ribbon-or clip-bond element 8), the problem of damages caused by thick Cu wireson contact area 5 is avoided.

FIG. 10 shows a standard power (i.e., non-power) semiconductor chip 1which may be a sensor chip, e.g., a CCD or a MEMS (for instance apressure sensor chip), or a logic circuit. Semiconductor chip 1 is ahorizontal semiconductor device. An active region 20 of thesemiconductor chip 1 is arranged in a central part at the upper side ofthe semiconductor chip 1.

Within the active region 20 are located contact areas 5, which may bemade of Cu or Al. These contact areas 5 are interconnected to post areas3 a provided on a leadframe or another semiconductor chip carrier (notshown) by bond wires 8 made of Al. The bond wires 8 are connected topost areas 3 a and contact areas 5 by a wedge bonding process.

A non-active region 21 of the semiconductor chip 1 extends between theactive region 20 and a periphery of the semiconductor chip 1. In thisnon-active region 21 contact areas 6 are located. These contact areas 6are interconnected to post areas 4 a provided on the leadframe orsemiconductor chip carrier (not shown) by bond wires 7 made of amaterial on the basis of Cu. The bond wires 7 are connected to postareas 4 a by a wedge bonding process and to contact areas 6 by a ballbonding process, respectively.

Such implementation may be beneficial because on the one hand, there isno risk that the Cu bond wires 7, which may be chip-bonded with a costefficient but pressure applying ball bonding process, damage activestructures of the semiconductor chip 1, and on the other hand, thecontact areas 5, which are bonded by Al bond wires 8 using a lowpressure wedge bonding process, may be placed within the active region20 of the semiconductor chip 1. Therefore, as the active region 20 andthe non-active region 21 may be used for bonding the semiconductor chip1, the size of the semiconductor chip 1 may be reduced.

In view of the above, the modules shown in FIGS. 1 to 10 may inparticular be designed according to the following principles.

A non-power semiconductor chip 1, e.g., a logic circuit chip with Cucontact areas 6, is mounted on a leadframe 11 made of Cu. Bond wire 7 ismade of Cu to minimize corrosion at the conductive contact area 6 on thesemiconductor chip 1 and the post area 4 a on lead 4. Bond wire 8 is forinstance made of Au in order to prevent damage of conductive contactarea 5 on semiconductor chip 1, or to prevent damage to the activeregion (e.g., sensor region) of the chip situated just below the contactarea.

A power semiconductor chip 1 is mounted on a leadframe 11 made of Cu.Bond wire 7 is made of Cu to minimize corrosion at the conductivecontact area 6 on the semiconductor chip 1 and the post area 4 a on lead4. Bond wire 8 is made of Al in order to provide a large diameter forhigh currents.

A power semiconductor chip 1 is mounted on a leadframe 11 made of Cu.Bond wire 7 is made of Cu to minimize corrosion at the conductivecontact area 6 on the semiconductor chip 1 and the post area 4 a on lead4. Bond element 8 is a ribbon bond element made of Al or Cu in order toallow for still higher currents than attainable by an Al bond wire.

A power semiconductor chip 1 is mounted on a leadframe 11 made of Cu.Bond wire 7 is made of Cu to minimize corrosion at the conductivecontact area 6 on the semiconductor chip 1 and the post area 4 a on lead4. Bond element 8 is a clip bond element made of Al or Cu in order toallow for still higher currents than attainable by a ribbon-bondelement.

Typically, the modules shown in FIGS. 1 to 10 are packaged. FIG. 7illustrates an embodiment in which the module shown in FIG. 3 comprisesa mold compound package 15. As an example, a three-terminal TO 252package 15 may be used. Possible dimensions of such package 15 areindicated in FIGS. 7 to 9 in units of mm. As may be seen in the bottomview (FIG. 9), the package 15 may have a footprint of 5.8 mm×6.4 mm.Including leads 3, 4, the module may have a length of 10.6 mm. Ofcourse, other dimensions as indicated in FIGS. 3 to 5 are possible.

A heat sink 16 may be contacted to the bottom of the die pad 10 andprotrude out of the package 15.

FIG. 11 illustrates steps of a wedge bonding process which may beapplied for bonding the bond wire 8 to the contact area 5 on thesemiconductor chip 1. The bond wire 8 extends through a capillary tool20 and may be clamped therein by a wire clamp 21. In a first step, thecapillary tool 20 is positioned over the contact area 5 and lowered tothe surface of the contact area 5. The bond wire 8 is pressed on thesurface of the contact area 5 by applying a specific pressure by meansof the capillary tool 20 (FIG. 11 a). Further, ultra-sonic energy isapplied. The combination of pressure and ultra-sonic energy at ambienttemperature results in a fusion of the wire material and the contactarea material, which causes the bond wire 8 to adhere to the contactarea 5. Then, the capillary tool 20 is lifted with released wire clamp21 (FIG. 11 b) and is transferred to and repositioned over post area 3 aof lead 3. On post area 3 a, a second wedge bonding process is carriedout. Then, the bond wire 8 is clamped by the wire clamp 21 and thecapillary tool 20 is lifted. Due to the adhesion of the bond wire 8 onthe post area 3 a, the bond wire 8 breaks (FIG. 11 c) and the wedge bondconnection is finished. Wedge bonding is carried out typically with bondwires made of Al or Cu. Bonding a wire with the wedge of a capillarytool leaves a typical foot shaped bond contact on the contact area thathas a flat region and a heel (see FIG. 11 b). In order not to overbendor break the heel region of the bond contact, the bond wire 8 is drawnin a direction away from the wedge bond foot.

FIG. 12 depicts process steps of a ball wire bonding process. In theball wire bonding process, also a capillary tool 20 equipped with a wireclamp 21 is used. In a first step, a ball 23 is formed at the end of thewire 7 (e.g., made on the basis of Cu) protruding out of the capillarytool 20. Ball formation may be performed by an electric flame-off sparkgenerated between a spark electrode 22 and the end of bond wire 7 (12a). After ball formation, the capillary tool 20 is positioned over thecontact area 6 on the semiconductor chip 1 and lowered to the surfacethereof (FIG. 12 b). Then, the ball 23 is welded on the contact area 6by the application of pressure, ultra-sonic energy and thermal energy,i.e., heat (FIG. 12 c). After the weld formation, the capillary tool 20is lifted with released wire clamp 21 and repositioned over post area 4a of lead 4 (not shown in FIG. 12; see e.g., FIG. 10). On post area 4 a,a wedge bonding process similar to that explained in conjunction withFIG. 11 may be performed to break the bond wire 7. Alternatively, a ballbonding process or a nailhead bonding process may be used on post area 4a.

Ball bonding is carried out typically with bond wires made of Au or Cu.As ball bonding creates a rotationally symmetric bond foot (see FIG. 12c), bond wire 7 can be drawn in any lateral direction when starting outfrom the bond foot.

Thus, it is to be noted that the terms wedge bonding and ball bondingrelate to the type of bonding bond wires 7, 8 to the chip contact areas6 and 5, respectively. Bonding to the post areas 4 a, 3 a on leads 4 and3 may be both accomplished by a wedge bonding process. Morespecifically, the term ball bonding comprises the process combinationsball-wedge, ball-nailhead and ball-ball, whereas the term wedge bondingcomprises the combination wedge-wedge.

FIG. 13 illustrates a flow chart of a process used for manufacturing amodule. At step S1, a semiconductor chip 1 with a control signal contactarea 6 and a load current contact area 5 is provided. Then, at step S2,the load current contact area 5 is interconnected to an externalterminal lead 3 of the module by a wedge bonding process performed atcontact area 6. At step S3, the control signal contact area 6 of thesemiconductor chip 1 is interconnected to another external terminal lead4 by a ball bonding process performed at contact area 6. Step S2 may becarried out prior to the step S3, but it is also possible that step S3is performed prior to or concurrently with step S2.

FIG. 14 schematically depicts a production line comprising a first wirebonding apparatus 100 and a second wire bonding apparatus 110, which areused in line processing for manufacturing modules. By way of example,the first wire bonding apparatus 100 uses a wedge-wedge wire bondingprocess (see e.g., FIG. 11) whereas the second wire bonding apparatus110 uses a ball-wedge wire bonding process (see e.g., FIG. 12). Thefirst wire bonding apparatus 100 is fed by a leadframe strip 120comprising a series of connected leadframes as, e.g., depicted in FIG.3. A semiconductor chip 1 is mounted on each leadframe 11. In the firstwire bonding apparatus 100, the Al bond wires 8 are applied. Theleadframe strip 120, which remains continuous, is then fed into thesecond wire bonding apparatus 110, which here is a ball wire bondingapparatus. In the ball wire bonding apparatus 110, the Cu wire bonds areapplied. The leadframes 11 are then separated (not shown) downstream ofthe second wire bonding apparatus 110.

Alternatively, as depicted in FIG. 15, the first wire bonding apparatus100 may process the continuous leadframe strip 120, whereas the secondwire bonding apparatus 110 (e.g., a ball wire bonding apparatus) mayprocess batches of one or more separate leadframes 11 with attachedsemiconductor chips 1. A separation of the leadframe strip 120 intosingle leadframes 11 is performed by a separating station 130 arrangedin between the first wire bonding apparatus 100 and the second wirebonding apparatus 110. Again, it is to be noted that the succession ofthe wedge bonding step and the ball bonding step may be reversed andthat it is also possible to perform both bonding processes within onecommon wire bonding apparatus.

1. A method for bonding a chip to a carrier, the method comprising: ballwire bonding a bond wire between a first terminal contact surface of thechip and a first contact of the carrier, wherein the bond wire comprisesa first material; and wedge wire bonding a bond element between a secondterminal contact surface of the chip to a second contact of the carrier,wherein the bond element comprises a second material, and wherein thesecond material is different than the first material.
 2. The methodaccording to claim 1, wherein wedge wire bonding is performed prior tothe ball wire bonding.
 3. The method according to claim 1, wherein ballwire bonding is performed prior to the wedge wire bonding.
 4. The methodaccording to claim 1, wherein the first terminal contact is a gatecontact of a transistor, and wherein the second terminal contact is asource or a drain contact of the transistor.
 5. The method according toclaim 1, wherein the second material comprises aluminum (Al) or gold(Au).
 6. The method according to claim 1, wherein the bond elementcomprises a ribbon-bond element or a clip bond element.
 7. The methodaccording to claim 1, wherein the chip comprises a power semiconductorchip, a MEMS or a CCD.
 8. A method for bonding a semiconductor chip to aleadframe, the method comprising: ball wire bonding a bond wire betweena first terminal contact surface of a transistor disposed in thesemiconductor chip and a first lead of the leadframe, wherein the bondwire comprises copper (Cu); and wedge wire bonding a bond elementbetween a second terminal contact surface of the transistor of thesemiconductor chip to a second lead of the leadframe, wherein the secondbond element comprises a material different from copper (Cu).
 9. Themethod according to claim 8, wherein the first lead and the second leadcomprise the same material.
 10. The method according to claim 8, whereinthe first terminal contact is a gate contact, and wherein the secondterminal contact is a source contact.
 11. The method according to claim8, wherein the material different from Cu comprises aluminum (Al) orgold (Au).
 12. The method according to claim 8, wherein the transistoris a vertical power transistor.
 13. The method according to claim 8,wherein the bond element comprises a ribbon-bond element or a clip bondelement.
 14. A method for manufacturing a semiconductor device, themethod comprising: placing a plurality of semiconductor chips on aleadframe strip, the leadframe strip comprises a series of connectedleadframes, wherein one semiconductor chip is placed on one leadframe;for each semiconductor chip, ball wire bonding a first bond wire betweena first terminal contact surface of the semiconductor chip and a firstcontact of a leadframe, wherein the first bond wire comprises a firstmaterial; for each semiconductor chip, wedge wire bonding a second bondwire between a second terminal contact surface of the semiconductor chipto a second contact of the leadframe, wherein the second bond wirecomprises a second material, and wherein the second material isdifferent than the first material; and forming the semiconductor deviceby singulating the leadframe strip.
 15. The method according to claim14, wherein wedge wire bonding comprises wedge wire bonding the secondbond wire to second terminal contact surface and wedge wire bonding thesecond bond wire to the second contact of the leadframe.
 16. The methodaccording to claim 15, wherein ball wire bonding comprises ball wirebonding the first bond wire to first terminal contact surface and wedgewire bonding the first bond wire to the first contact of the leadframe.17. The method according to claim 16, wherein the second bond wirecomprises a clip bond element or a ribbon bond element.
 18. The methodaccording to claim 17, wherein the first material is Cu and wherein thesecond material is Al.
 19. The method according to claim 14, wherein thefirst terminal contact surface is a control terminal and the secondterminal contact surface is a load terminal of a power semiconductorchip.
 20. The method according to claim 14, wherein one of the ball wirebonding or the wedge wire bonding is carried out before singulating theleadframe strip and then another of the ball wire bonding or the wedgewire bonding is carried out after singulating the leadframe strip.